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Elwha Dam
The Elwha Dam was a 108-ft (33 m) high dam located in the United States, in the state of Washington, on the Elwha River approximately upstream from the mouth of the river on the Strait of Juan de Fuca. The Elwha River Ecosystem and Fisheries Restoration Act of 1992 authorized the US Federal Government to acquire the Elwha Dam and Glines Canyon Dam hydroelectric power projects for decommissioning and demolition for habitat restoration. Removal of the Elwha Dam began in September 2011 and was fully complete by March 2012, allowing the Elwha River to flow freely through the site. Construction The dam was built under the direction of Thomas Aldwell. He previously bought up tracts of land around the river, and with the help of Canadian financier George Glines, began construction of the Elwha Dam in 1910. Aldwell and his contractors cut corners on constructing the dam, including illegally not building fish passages and not securing it to the bedrock. Thus, in 1912, as the reservo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elwha River
The Elwha River is a river on the Olympic Peninsula in the U.S. state of Washington (state), Washington. From its source at Elwha snowfinger in the Olympic Mountains, it flows generally north to the Strait of Juan de Fuca. Most of the river's course is within the Olympic National Park. The Elwha is one several rivers in the Pacific Northwest that hosts all five species of native Pacific salmon (Chinook salmon, chinook, coho salmon, coho, chum salmon, chum, sockeye salmon, sockeye, and pink salmon), plus four Fish migration, anadromous trout species (Rainbow trout, steelhead, coastal cutthroat trout, bull trout, and Dolly Varden char). From 1911 to 2014, dams blocked fish passage on the lower Elwha River. Before the dams, 400,000 adult salmon returned yearly to spawn in of river habitat. Prior to dam removal, fewer than 4,000 salmon returned each year in only of habitat below the lower dam. The National Park Service removed the two dams as part of the $325 million Elwha Ecosyste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anadromous
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear. Fish migrations involve movements of schools of fish on a scale and duration larger than those arising during normal daily activities. Some particular types of migration are ''anadromous'', in which adult fish live in the sea and migrate into fresh water to spawn; and ''catadromous'', in which adult fish live in fresh water and migrate into salt water to spawn. Marine forage fish often make large migrations between their spawning, feeding and nursery grounds. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bull Trout
The bull trout (''Salvelinus confluentus'') is a char of the family Salmonidae native to northwestern North America. Historically, ''S. confluentus'' has been known as the " Dolly Varden" (''S. malma''), but was reclassified as a separate species in 1980. Bull trout are listed as a threatened species under the U.S. Endangered Species Act (1998) and as vulnerable on the IUCN Red List of Threatened Species. Description Like other species of char, the fins of a bull trout have white leading edges. Its head and mouth are unusually large for salmonids, giving it its name. Bull trout have been recorded measuring up to in length and weighing . Bull trout may be either migratory, moving throughout large river systems, lakes, and the ocean, or they may be resident, remaining in the same stream their entire lives. Migratory bull trout are typically much larger than resident bull trout, which rarely exceed . Bull trout can be differentiated from brook trout (''S. fontinalis'') by the absen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutthroat Trout
The cutthroat trout is a fish species of the family Salmonidae native to cold-water tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. As a member of the genus '' Oncorhynchus'', it is one of the Pacific trout, a group that includes the widely distributed rainbow trout. Cutthroat trout are popular gamefish, especially among anglers who enjoy fly fishing. The common name "cutthroat" refers to the distinctive red coloration on the underside of the lower jaw. The specific name ''clarkii'' was given to honor explorer William Clark, coleader of the Lewis and Clark Expedition. Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well- oxygenated, shallow rivers with gravel bottoms. They reproduce in clear, cold, moderately deep lakes. They are native to the alluvial or freestone streams that are typical tributaries of the rivers of the Pacific Basin, Great Basin and Rocky Mountains. Cutthroat trout spawn in the spring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steelhead
Steelhead, or occasionally steelhead trout, is the common name of the anadromous form of the coastal rainbow trout or redband trout (O. m. gairdneri). Steelhead are native to cold-water tributaries of the Pacific basin in Northeast Asia and North America. Like other sea-run (anadromous) trout and salmon, steelhead spawn in freshwater, smolts migrate to the ocean to forage for several years and adults return to their natal streams to spawn. Steelhead are iteroparous, although survival is approximately 10–20%. Description The freshwater form of the steelhead is the rainbow trout (''Oncorhynchus mykiss''). The difference between these forms of the species is that steelhead migrate to the ocean and return to freshwater tributaries to spawn, whereas non-anadromous rainbow trout do not leave freshwater. Steelhead are also larger and less colorful than rainbow trout, and can weigh up to and reach in length. They can live up to 11 years and spawn multiple times. The body of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sockeye Salmon
The sockeye salmon (''Oncorhynchus nerka''), also called red salmon, kokanee salmon, blueback salmon, or simply sockeye, is an anadromous species of salmon found in the Northern Pacific Ocean and rivers discharging into it. This species is a Pacific salmon that is primarily red in hue during spawning. They can grow up to in length and weigh . Juveniles remain in freshwater until they are ready to migrate to the ocean, over distances of up to . Their diet consists primarily of zooplankton. Sockeye salmon are semelparous, dying after they spawn. Some populations, referred to as kokanee, do not migrate to the ocean and live their entire lives in fresh water. Classification and name origin The sockeye salmon is the third-most common Pacific salmon species, after pink and chum salmon. ''Oncorhynchus'' comes from the Greek ὄγκος (onkos) meaning "barb", and ῥύγχος (rhynchos) meaning "snout". ''Nerka'' is the Russian name for the anadromous form. The name "sockeye" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pink Salmon
Pink salmon or humpback salmon (''Oncorhynchus gorbuscha'') is a species of anadromous fish in the salmon family. It is the smallest and most abundant of the Pacific salmon. The scientific species name is based on the Russian common name for this species ''gorbúša'' (горбуша), which literally means ''humpie''. Description In the ocean, pink salmon are bright silver fish. After returning to their spawning streams, their coloring changes to pale grey on the back with yellowish-white belly (although some turn an overall dull green color). As with all salmon, in addition to the dorsal fin, they also have an adipose fin. The fish is characterized by a white mouth with black gums, no teeth on the tongue, large oval-shaped black spots on the back, a v-shaped tail, and an anal fin with 13-17 soft rays. During their spawning migration, males develop a pronounced humped back, hence their nickname "humpies". Pink salmon average 4.8 pounds (2.2 kg) in weight. The maximu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chum Salmon
The chum salmon (''Oncorhynchus keta''), also known as dog salmon or keta salmon, is a species of anadromous salmonid fish from the genus '' Oncorhynchus'' (Pacific salmon) native to the coastal rivers of the North Pacific and the Beringian Arctic, and is often marketed under the trade name silverbrite salmon in North America. The English name "chum salmon" comes from the Chinook Jargon term ''tzum'', meaning "spotted" or "marked"; while ''keta'' in the scientific name comes from Russian, which in turn comes from the Evenki language of Eastern Siberia. In Japan, chum salmon is also known as the , or simply , while historically it was known in ''kun'yomi'' as up until the Meiji period. In Greater China, it is known academically as the " hook-snout salmon" ( zh, 钩吻鲑), but is more often called the ''damaha'' fish (), which is borrowed from ''dawa ịmaχa'', the Nanai name of the fish used by the Hezhe minority in northern Northeast China. Description The body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coho Salmon
The coho salmon (''Oncorhynchus kisutch;'' Karuk: achvuun) is a species of anadromous fish in the salmon family and one of the five Pacific salmon species. Coho salmon are also known as silver salmon or "silvers". The scientific species name is based on the Russian common name ''kizhuch'' (кижуч). Description During their ocean phase, coho salmon have silver sides and dark-blue backs. During their spawning phase, their jaws and teeth become hooked. After entering fresh water, they develop bright-red sides, bluish-green heads and backs, dark bellies and dark spots on their backs. Sexually maturing fish develop a light-pink or rose shading along the belly, and the males may show a slight arching of the back. Mature adults have a pronounced red skin color with darker backs and average and , occasionally reaching up to . They also develop a large kype (hooked beak) during spawning. Mature females may be darker than males, with both showing a pronounced hook on the nose. Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dam Removal
Dam removal is the process of demolishing a dam, returning water flow to the river. Arguments for dam removal consider whether their negative effects outweigh their benefits. The benefits of dams include hydropower production, flood control, irrigation, and navigation. Negative effects of dams include environmental degradation, such as reduced primary productivity, loss of biodiversity, and declines in native species; some negative effects worsen as dams age, like structural weakness, reduced safety, sediment accumulation, and high maintenance expense. The rate of dam removals in the United States has increased over time, in part driven by dam age. As of 1996, 5,000 large dams around the world were more than 50 years old. In 2020, 85% percent of dams in the United States are more than 50 years old. In the United States roughly 900 dams were removed between 1990 and 2015, and by 2015, the rate was 50 to 60 per year. France and Canada have also completed significant removal project ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood Control
Flood control methods are used to reduce or prevent the detrimental effects of flood waters."Flood Control", MSN Encarta, 2008 (see below: Further reading). Flood relief methods are used to reduce the effects of flood waters or high water levels. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Though building hard infrastructure to prevent flooding, such as flood walls, can be effective at managing flooding, increased best practice within landscape engineering is to rely more on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water. For flooding on coasts, coastal management practices have to not only handle changes water flow, but also natural processes like tides. Flood control and relief is a particularly important part of climate change adaptation and climate resilience, both sea level rise and changes in the weather (climate cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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